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17 correct example –t = acress – = acres (44%) despite all the math wrong result for –was called a stellar and versatile acress what does Microsoft Word use? –was called a stellar and versatile acress

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18 Minimum Edit Distance –textbook section 5.7 general string comparison edit operations are insertion, deletion and substitution not just limited to distance defined by a single operation away ( correct ) we can ask how different is string a from b by the minimum edit distance

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19 Minimum Edit Distance applications –could be used for multi-typo correction –used in Machine Translation Evaluation (MTEval) –example Source: 生産工程改善について Translations: (Standard) For improvement of the production process (MT-A) About a production process betterment (MT-B) About the production process improvement method –compute edit distance between MT-A and Standard and MT-B and Standard in terms of word insertion/substitution etc.

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21 Minimum Edit Distance Dynamic Programming –divide-and-conquer to solve a problem we divide it into sub-problems –sub-problems may be repeated don’t want to re-solve a sub-problem the 2nd time around –idea: put solutions to sub-problems in a table and just look up the solution 2nd time around, thereby saving time memoization